Non-load bearing masonry block containing crumb rubber

ABSTRACT

Crumb Rubber augmented masonry blocks including cement, aggregate, water, and crumb rubber. Crumb rubber is extracted from scrape tires after being processed and then mixed in specified percentages with aggregate, cement and water. In the present disclosure sand, which is used in the formation of conventional blocks, is replaced with crumb rubber to produce a sand-free masonry block containing crumb rubber. The developed crumb rubber masonry blocks satisfied the ASTM non-load bearing requirements in addition to satisfying the water absorption test.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part (CIP) of, and thus claims thebenefit of, U.S. application Ser. No. 14/253,978 filed Apr. 16, 2014,incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to a masonry block in which crumb rubbermaterial replaces sand in a masonry block comprising cement, aggregate,crumb rubber and water.

Description of the Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described. in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

A search for innovative, environmentally friendly and ready-to-usebuilding composites that combine higher efficiency and quality in thebuilding process with improved thermal resistance has been ongoing. Thishas set increased demands on the both thermal and mechanical(thermo-mechanical) performances of new building products integratedwith various plasters, foils, particles and rubbers. The large demand onbuilding material industry has resulted from the increasing population,leading to a chronic shortage of building materials. The engineers havethen been challenged to convert the industrial wastes to useful buildingand construction materials. Accumulation of unmanaged wastes is one oftoday's significant environmental concerns, especially in developingcountries. Recycling of such wastes as building materials appears to bea viable solution not only to such pollution problem but also to theproblem of the economical design of buildings. The increase in thepopularity of using environmentally friendly, low cost and lightweightconstruction materials in building industry brings the need forsearching more innovative, flexible and versatile composites. The mostimportant aspects of innovation might be in the development ofintegrated insulation products such as the insulated, reinforcedconcretes, two or three-way precast sandwich wall panels, and rubberizedconcretes. Part of this interest is to establish the thermal performanceof the alternative systems and products. Accurate thermalcharacteristics are required to guide product development andmanufacturing. Methods and data exist for dealing with the commonbuilding walls and insulations, but new systems and products aregenerally lacking such data.

One of the new and popular products in this sense is modifiedcementitious composites with scrap tire rubber. Use of rubber from scraptires in cement concrete mixtures can result in large benefits, likelower density, increased toughness and ductility, higher impactresistance, and more efficient heat and sound insulation. The use ofrecycled tire rubber also helps alleviate disposal problems and addressthe growing public concern about the need to preserve natural sand andaggregates.

Accumulations of discarded waste tires have been a major concern becauseof waste rubber is not easily biodegradable even after a long-period.Landfill treatment and unmanaged waste tires represent an environmentaland health risk through fire hazard and as a breeding ground fordisease-carrying mosquitoes. The alternatives are thus oriented towardmaterials and energy recovery.

A brick is the most basic building material for construction of low costhouses and apartments. Conventional types of brick are made from burntclay and a significant quantity of fuel is consumed during itsproduction.

Crumb rubber is produced by stepwise grinding of used tires. The crumbrubber can be used in different industries such as rubberized asphalt,mats production, and play ground athletic fields. Production of crumbrubber composites will open up a new market for crumb rubber.

BRIEF SUMMARY OF THE INVENTION

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

According to a first aspect, the present disclosure relates to a masonryblock involving i) 20-30 wt % cement, ii) 50-60 wt % of an aggregate,which is not crumb rubber, iii) 1-10 wt % water, and iv) 10-20 wt %crumb rubber relative to the total weight of the masonry block. Thecrumb rubber present in the masonry block is in the form of coarseparticles having a particle size of 1.5-5 mm, fine particles having aparticle size of 50-250 μm, or a mixture of the coarse particles and thefine particles.

In one embodiment, the crumb rubber is in the form of coarse particleshaving a particle size of 1.5-5 mm.

In one embodiment, the crumb rubber is in the form of fine particleshaving a particle size of 50-250 μm. In one embodiment, the fineparticles have a particle size of 100-148 μm.

In one embodiment, the mixture of the coarse particles and fineparticles is present.

In one embodiment, a ratio of the coarse particles to the fine particlesranges from 2:1 to 1:2.

In one embodiment, the ratio of the coarse particles to the fineparticles is about 1:1.

In one embodiment, the masonry block has a unit weight of 1000-1250kg/m³.

In one embodiment, the masonry block has a water absorption of 6.0-9.0%as deter lined by ASTM C 642.

In one embodiment, the aggregate is a crushed recycled concretematerial.

In one embodiment, no aggregate, filler, or additive which comprises agroup 13 element is present in the masonry block. In one embodiment, thegroup 13 element is boron.

In one embodiment, the crumb rubber is silanized crumb rubber obtainedby treating crumb rubber with a silanizing agent selected from the groupconsisting of an aminosilane, a glycidoxysilane, and a mercaptosilane.In one embodiment, the aminosilane is selected from the group consistingof (3-aminopropyl)-diethoxy-methylsilane,(3-aminopropyl)-dimethyl-ethoxysilane, and(3-aminopropyl)-trimethoxysilane. In one embodiment, the glycidosilaneis (3-glycidoxypropyl)-dimethyl-ethoxysilane. In one embodiment, themercaptosilane is (3-mercaptopropyl)-trimethoxysilane or(3-mercaptopropyl)-methyl-dimethoxysilane.

In one embodiment, the crumb rubber is carboxylic acid surface modifiedcrumb rubber obtained by treating crumb rubber with hydrogen peroxide.

In one embodiment, the masonry block has a wt % of crumb rubber rangingfrom 12 to 18%, relative to the total weight of the masonry block.

In one embodiment, the masonry block consists of the cement, theaggregate, the water and the crumb rubber.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a conventional masonry block;

FIG. 2 illustrates a crumb-rubber augmented masonry block.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure will now be described more fullyhereinafter with reference to the accompanying drawings, in which some,but not all embodiments of the disclosure are shown.

One embodiment of the disclosure describes Crumb Rubber (CR) augmentedMasonry Blocks. In one embodiment, crumb rubber is obtained from scraptires after being processed. The crumb rubber is then mixed in specifiedpercentages with aggregate particles, cement and water. The conventionalprocessing of Masonry blocks includes mixing aggregate, cement water,and 15% of sand. The sand is typically about 10-20% of the masonryblock. Preferably, about 15% of the conventional masonry block is sand.Sand is a naturally occurring granular material composed of finelydivided rock and mineral particles. The composition of sand may varydepending on the local rock sources and conditions, but the most commonconstituent of sand in inland settings includes SiO₂ in the form ofquartz. Sand is in particulate form, e.g., grains having a diameter offrom 0.0625 mm or less to about 2 mm.

Any type of cement or cement containing material may be used in any ofthe embodiments disclosed herein. For example, cement may include typeI, Type 1a, type II, type IIa, type III, type IIIa, type IV and type VPortland cements (using either the ASTM 0150 standard or the EuropeanEN-197 standard), hydraulic cements, non-hydraulic cements, Portlandflyash cement, Portland Pozzolan cement. Portland silica fume cement,masonry Cements, mortars,EMC cements, stuccos, plastic cements,expansive cements, White blended cements, Pozzolan-lime cements,slag-lime cements, supersulfated cements, calcium aluminatecements,calcium sulfoaluminate cements, geopolymer cements, Rosendalecements, polymer cement mortar, lime mortar, and/or Pozzolana mortar.

In one embodiment SiO₂ may be present in cement. Cement may includeSiO₂-containing materials including but not limited to belite(2CaO.SiO₂), alite (3CaO.SiO₂), celite (3CaO.Al₂O₃), or brownmillerite(4CaO.Al₂O₃.Fe₂O₃) commonly found in sand-free cement.

In one embodiment the masonry blocks are made by mixing cement withcrumb rubber in the absence of sand. In another embodiment the masonryblocks are made with cement containing sand and mixing the cement withcrumb rubber. Preferably no sand is present as an aggregate component inthe masonry block.

In the present disclosure, sand is replaced with crumb rubber to form amasonry block comprising cement, an aggregate, water (which may be inreacted form after curing), and crumb rubber. In one embodiment, themasonry block consists of cement, an aggregate, water, and crumb rubber.

The crumb rubber-augmented masonry blocks may include a wt % of cementin the range of 20-30%, or 21-29%, or 22-28%, or 23-27%, or 24-26%, or25%, relative to the total weight of the masonry block. The crumbrubber-augmented masonry blocks may include a wt % of aggregate (whichis not crumb rubber) in the range of 50-60%, or 51-59%, or 52-58%, or53-57%, or 54-56%, or 55% relative to the total weight of the masonryblock. The crumb rubber-augmented masonry blocks may include a wt % ofwater in the range of 1-10%, or 2-9%, or 3-8%, or 4-7% or 5% relative tothe total weight of the masonry block. The crumb rubber-augmentedmasonry blocks may include a wt % of crumb rubber in the range of10-20%, or 11-19%, or 12-18%, or 13-17%, or 14-16%, or 15% relative tothe total weight of the masonry block. Preferably, the crumb rubberaugmented masonry block may have a wt % composition that includes 25%cement, 55% aggregate, 5% water, and 15% crumb rubber, or 30% cement,55% aggregate, 5% water, and 10% crumb rubber, or 25% cement, 50%aggregate, 10% water, and 20% crumb rubber.

Crumb rubber is usually retrieved from recycled tires that are ground toabout the size of a lump of coal. Thereafter these nuggets are grounddown to about walnut size, with further grinding techniques bringing thewalnut size bits of rubber down to mesh sizes to a lower mesh size. Thecrumb rubber may be in the form of coarse particles having a particlesize of 1.5-5 mm, fine particles having a particle size of 50-250 μm, ora mixture of the coarse particles and the fine particles.

In one embodiment, the crumb rubber is in the form of coarse particleshaving a particle size of 1.5-5 mm, or 1.6-4.5 mm, or 1.7-4 mm, or1.8-3.5 mm, or 1.9-3.2 mm, or 2-3 mm.

In one embodiment, the crumb rubber is in the form of fine particleshaving a particle size of 50-250 p.m, or 60-240 μm, or 70-230 μm, or80-220 or 90-210 μm, or 100-200, or 100-180 μm, or 100-160 μm, or100-150 μm, or 100-148 μm or, 100-140 μm. Preferably, the fine particlesof crumb rubber have a mesh size of 65-100 mesh, 70-100 mesh, 75-95mesh, 80-90 mesh, or an 80 mesh (177 μm) size.

In one embodiment, the mixture of the coarse particles and fineparticles is present. A ratio of the coarse particles to the fineparticles (by weight) may range from 2:1 to 1:2, or 1.9:1 to 1:1.9, or1.8:1 to 1:1.8, or 1.7:1 to 1:1.7, or 1.6:1 to 1:1.6, or 1.5:1 to 1:1.5,or 1.4:1 to 1:1.4, or 1.3:1 to 1:1.3, or 1.2:1 to 1:1.2, or 1.1:1 to1:1.1, or about 1:1.

In one embodiment, the crumb rubber particles of the present disclosureare treated with a surface treatment agent such as hydrogen peroxide toforum treated particles having more carboxylic sites than untreatedparticles. The functional groups in the mixture containing water,aggregate, and cement then interact with the carboxylic sites, therebycausing the treated crumb rubber particles to contact with and besuspended in the mixture to a much greater degree than untreatedparticles.

Preferably, the crumb rubber particles are as small as possible so thatthey are most easily suspended in the mixture. The particles can betreated by mixing them with hydrogen peroxide at a temperature of about65-85 degrees Centigrade while stirring for about 20 to 30 minutes toproduce a freely-flowing powder. Preferably, the amount of hydrogenperoxide used is 0.035-0.040 milli-moles of peroxide per gram ofmixture.

In another embodiment of the disclosure, the crumb rubber may also becompressed at high pressure at the presence of a specialized urethane,sodium silicate or any other acceptable glues. Preferably, the crumbrubber is compressed at a high pressure in the presence of a sodiumsilicate. In one embodiment, the applied pressure is stepped until thecrumb rubber is flowable by first applying 1600 PSI and then in 15second intervals stepping up the pressure by 500 PSI until the pressurereaches 3600 PSI.

In another embodiment the crumb rubber can be treated with a silanizingagent including but not limited to aminosilanes, glycidoxysilanes, andmercaptosilanes. Such aminosilanes include but are not limited to(3-aminopropyl)-diethoxy-methylsilane,(3-aminopropyl)-dimethyl-ethoxysilane, and(3-aminopropyl)-trimethoxysilane. Such glycidoxysilanes include but arenot limited to (3-glycidoxypropyl)-dimethyl-ethoxysilane. Suchmercaptosilanes include but are not limited to(3-mercaptopropyl)-trimethoxysilane and(3-mercaptopropyl)-methyl-dimethoxysilane. The organofunctionalalkoxysilane group of the silanizing agent interacts with the hydroxylgroups of the crumb rubber to displace the alkoxy groups attached to thesilane molecule. A crumb rubber matrix containing the silanized crumbrubber is formed.

Exemplary aggregates include crushed recycled concrete, gravel, rocks,natural soil, quarried crushed mineral aggregates from igneous,metamorphic or sedimentary rocks, including unused and waste aggregatesfrom quarry operations, gravel, dredged aggregates, china clay stent,china clay wastes, natural stone, recycled bituminous pavements,recycled concrete pavements, reclaimed road base and subbase materials,crushed bricks, construction and demolition wastes, waste/recycled fluegas ashes, crushed glass, slate waste, waste plastics, egg shells, seashells, and mixtures thereof. In one embodiment, the aggregate iscrushed recycled concrete. The crushed recycled concrete can be made bycrushing, grinding, pulverizing, etc. any concrete material includingconcrete compositions that include sand as an aggregate, or morepreferably concrete material from the present disclosure (i.e. cement,aggregate which does not include sand, water, crumb rubber).

In one embodiment, no aggregate, filler, or additive which comprises agroup 13 element is present in the masonry block. In one embodiment, thegroup 13 element is boron. Examples of aggregates, fillers, or additivesthat contain boron include borosilicates, boric acid, boron carbide,boron containing fibers, boron containing fabrics, boron containingmesh, boron filaments, borax, boron oxide, ferro boron and boratedstainless steel, colemanite, ulexite, kemite, tincal, boron nitride,borates, or mixtures or boron isotopes thereof.

In one embodiment, the masonry block has a unit weight of 1000-1250kg/m³, preferably 1020-1200 kg/m³, preferably 1025-1150 kg/m³.Conventional masonry blocks have a unit weight of around 1259-1260kg/m³, therefore, the masonry block of the present disclosure may have aunit weight (in kg/m³) that is 10-20% lower than that of conventionalconcrete blocks, which can cause less weight to be placed on a buildingframe and less wear on any concrete handling machinery.

In one embodiment, the masonry block has a water absorption of 6.0-9.0%,or 6.5-8.98%, or 6.8-8.95%, or 6.9-8.93% as determined by ASTM C 642.

In one embodiment, the masonry block has a thermal conductivity of0.3-0.58 W/m·k, preferably 0.34-0.56 W/m·k, preferably 0.36-0.54 W/m·k,preferably 0.4-0.52 W/m·k. Conventional masonry blocks have a thermalconductivity of 0.585 W/m·k, and therefore the masonry blocks of thepresent disclosure (i.e. with crumb rubber) have a lower thermalconductivity which may provide energy conservation in buildingsemploying the crumb rubber masonry blocks.

The weight of the crumb rubber augmented masonry block is in the rangeof 10-30 kg, preferably 11-20 kg, preferably 15-20 kg, preferably 12-18kg, preferably 16-19 kg.

One embodiment includes a masonry block comprising crumb rubber,aggregate, cement, and water. In one embodiment, crumb rubber, cement,and aggregate are placed in a concrete mixer and dry mixed for a timeperiod in the range of 30 seconds-10 minutes, 45 seconds-8 minutes, or50 seconds-5 minutes. Preferably the crumb rubber, cement, and aggregateare dry mixed for 1 minute. Mixing the crumb rubber, cement, andaggregate forms a mixture in which the crumb rubber is homogenouslydispersed. Following the dry mixing process, water is added to themixture of crumb rubber, cement, and aggregate. The water is slowlypoured into a mixer while the mixer turns the cement, crumb rubber, andaggregate for a time period in the range of 1-10 minutes, 2-8 minutes,or 3-6 minutes. Preferably the water is mixed into the mixture for atime period of 3 minutes.

The mixture of water, crumb rubber, cement, and aggregate is fed into asteel mould to create a masonry block shape. The fresh mix is compactedin the mould by using a steel rod. After setting into the mould, themixture is air cured for a time period in the range of 1-10 hours, 2-8hours, or 4-7 hours. Preferably the mixture is air cured in the mouldfor a time period of 6 hours and then removed from the mould, whichresults in a masonry block. The masonry block is then cured for a timeperiod of 15-30 days in a cure tank filled with lime-saturated water ata temperature in the range of 20-30° C., 21-29° C. or 22-28° C.Preferably the masonry block sample is cured for a time period of 28days in a cure tank filled with lime-saturated water at a temperature of22° C.

In one embodiment, the crumb rubber is a thermoset or thermoplasticpolymer in the form of recycled crumb rubber from automotive and truckscrap tires.

In another embodiment the CR augmented masonry blocks don't require newprocessing routes as the same route used for producing conventionalblocks can be adopted.

In another embodiment the CR augmented masonry blocks satisfy thestandard for utilization in construction industry.

In another embodiment the CR augmented masonry blocks contributesignificantly in utilizing Crumb rubber which will be a motivation tostop burning car tires and start shredding them to obtain more CR forthe utilization in such application.

It has been observed that there is a physiological barrier in the publicto use products that are made out of CR (or waste tires, as they referto it). This has hindered the utilization of CR in importantapplications such as flooring and play grounds. The present embodimentutilizes CR in products and applications that are not in direct contactwith people in order to remove this limitation.

The scrapped tires cannot be considered a waste material since itcontains the needed Crumb Rubber that could be utilized. It is avaluable product with ongoing expansion and growth in diversifiedmarkets. It is far better to remove tires from the waste stream,regardless of disposal method, than to allow the continuation ofuncontrollable and disastrous waste tire stock fires throughout theworld. The extracted materials can be used as well once CRs is beingremoved from the tires. The CR-augmented Masonry blocks described in thedisclosure were able to pass the ASTM standards adopted for theutilization of Masonry blocks in non-loading applications in addition towater absorption.

Utilizing and recycling crumb rubber in industry will have a tremendousenviromnental impact since scrap tires are typically burned due to thelack of suitable utilization of the crumb nibber that is extracted fromthem.

The examples below are intended to further illustrate the masonryblocks, their characterization, and uses thereof, and are not intendedto limit the scope of the claims.

EXAMPLES

A comparative analysis was carried out between conventional masonryblocks and those augmented with CR. The developed CR-blocks displayed acombination of properties that satisfied the ASTM non-load bearingrequirements in addition to satisfying the water absorption test.

The current commercially available masonry blocks are composed ofaggregate, cemen water and sand and they are being utilized heavily inthe construction industry. In the present disclosure, sand is replacedwith crumb rubber using the same processing route. The crumb-rubberaugmented masonry block was evaluated for the performance of the Masonryblocks in conditions similar to the ones faced during their utilizationin the construction industry. The conventional masonry blocks arecomposed of the following ingredients with the listed percentages aslisted in Table 1:

TABLE 1 Percent Composition of Conventional Masonry Blocks IngredientPercentage Cement 25% Aggregate 55% Water 5% Sand 15%

FIG. 1 depicts conventional masonry blocks which have an average weightof 20.150 kg.

Table 2 displays an example of a percent composition of a crumb-rubberaugmented masonry block.

TABLE 2 Percent Composition of Crumb-Rubber Augmented Masonry BlocksIngredient Percentage Cement 25% Aggregate 55% Water 5% Crumb Rubber 15%

FIG. 2 displays the block fabricated with CR-augmentation which weighson average 17.6 kg.

Different sizes of CR were added to the developed blocks. Table 3 showsthe different sizes of CR and their composition.

TABLE 3 Specimen Size and composition designation CR type (by weight) FFine grained 100-200 μm (diameter) - 100% C Coarse grained 2-3 mm(diameter) - 100% FC Mixture of Fine and Coarse 50% fine (100-200 μm) +grained 50% coarse (2-3 mm)The nomenclature utilized to identify the types of blocks is as follows:

N—Normal Block

F—Block with fine crumb rubber (powder)

FC—Block with 50% fine crumb rubber (powder) and 50% coarse crumb rubber(mesh)

C—Block with coarse crumb rubber (mesh)

The unit weight of the conventional and developed CR masonry blocks arecompared in Table 4.

TABLE 4 Unit weight of conventional and developed CR masonry blocks.Specimen Oven dry Length, Width, Unit Weight, designation weight, g mmmm Height, mm kg/m³ N 20150.5 400 201 199 1259.44 F 16366.8 400 199 2001028.07 FC 17868.8 400 199 199 1128.05 C 18592.3 400 200 203 1144.85

As indicated by the data in Table 4, the unit weight of the developed CRmasonry blocks is less than that of the conventional masonry blocks. Onan average the unit weight of the CR masonry blocks is 10 to 25% lessthan that of the conventional blocks. The decrease in the unit weight ofthe CR masonry blocks will entail a lower weight on the building frameand also less wear tear on the handling machinery.

Multiple tests were performed on the crumb rubber augmented masonryblocks in order to assess any improvement in their characteristics.Compressive tests (both load bearing and non-load bearing) wereperformed in addition to water absorption for both conventional andCR-augmented blocks.

TABLE 5 Compressive strength of conventional and the developed CRmasonry blocks. ASTM C129 ASTM C90 Average requirement requirementCompressive Compressive for Non-load for load- Specimen Net area, Load,strength, strength, bearing bearing type mm² kN MPa MPa blocks blocks N47204 612.4 12.97 12.97 3.45 MPa if 11.7 MPa if F-1 46657 172.7 3.703.62 one specimen one specimen F-2 46901 165.5 3.53 is tested and istested and FC-1 47380 155.4 3.28 3.39 4.14 MPa for 13.1 MPa for FC-247653 166.4 3.49 average of average of C 46804 331.5 7.08 7.08 threethree specimens specimens

The developed CR masonry blocks were tested to their compressivestrength. The results of these tests are presented in Table 5. Thecompressive strength of the developed blocks are compared with that ofthe conventional blocks. Also, the ASTM requirements for non-loading andload-bearing blocks are presented in the last two columns of Table 5. Asis evident from the data in Table 5, the compressive strength theconventional blocks was 12.97 MPa while it was in the range of 3.4 to7.1 MPa in the CR masonry blocks. While the conventional blocks meet theASTM requirements for both non-load bearing and load-bearing blocks, thedeveloped blocks satisfy the requirements for the non-load bearingblocks. Since masonry blocks are utilized as non-load bearing units, thedeveloped CR masonry blocks can be used beneficially utilized due totheir low weight compared to the conventional masonry blocks.

TABLE 6 Water absorption of conventional and developed CR masonryblocks. Water Specimen type Oven dry weight, g SSD weight, g absorption,% N 20150.5 21239.5 5.40 F 16366.8 17827.5 8.92 FC 17868.8 19130.3 7.06C 18592.3 19884.6 6.95

The water absorption of conventional and developed CR masonry blocks issummarized in Table 6. The water absorption of the developed CR masonryblocks is in the range of 6.95 to 8.92% while it is 5.4% in theconventional blocks. Water absorption of both the blocks is within theacceptable limit particularly since they are generally coated withcement plaster or coal tar coating. The acceptable limit of wateradsorption for the water adsorption test is less than 10% wateradsorption under standard working conditions and a standard environment.The CR augmented masonry blocks have a higher water absorption capacitythan the conventional masonry blocks.

TABLE 7 Thermal conductivity of the CR masonry blocks and conventionalblocks. Test Thermal Dimensions, Thickness, temperature, conductivity,Specimen type cm × cm × cm cm ° C. W/m · K N-Normal 40 × 20 × 20 20.0933.3 0.585 block (without CR) F-block with 40 × 20 × 20 19.95 35.3 0.403fine CR (powder) FC-Block with 40 × 20 × 20 20.07 36.1 0.414 (50% Fine +50% Coarse CR) C-Block with 40 × 20 × 20 20.04 35.0 0.512 Coarse CR(mesh)

The thermal conductivity of the developed CR masonry blocks is comparedwith that of the conventional blocks in Table 7. The thermalconductivity of conventional blocks is 0.585 W/m·K while it is in therange of 0.403 to 0.512 W/m·K in the developed CR masonry blocks. Thedecrease in the thermal conductivity of the developed Cr masonry blockswill be helpful in energy conservation in buildings.

It can be seen from the conducted tests that CR-augmented masonry blocksmeet the requirement ASTM requirements for strength of non-load bearingblocks and exhibited reasonable improvement in thermal characteristics.The addition of different percentages and types of crumb rubber provedto alter the properties of the developed blocks.

1. A sand-free non-load bearing masonry block, comprising: 20-30 wt %cement; 50-60 wt % of an aggregate, which is not crumb rubber; 1-10 wt %water; and 10-20 wt % crumb rubber relative to the total weight of themasonry block; wherein the crumb rubber is in the form of coarseparticles having a particle size of 1.5-5 mm, fine particles having aparticle size of 50-250 μm, or a mixture of the coarse particles and thefine particles and is surface treated with at least one of a silane andhydrogen peroxide, wherein the masonry block has a thermal conductivityof 0.3-0.58 W/m·K.
 2. The masonry block of claim 1, wherein the crumbrubber is in the form of coarse particles having a particle size of1.5-5 mm.
 3. The masonry block of claim 1, wherein the crumb rubber isin the form of fine particles having a particle size of 50-250 μm. 4.The masonry block of claim 3, wherein the fine particles have a particlesize of 100-148 μm.
 5. The masonry block of claim 1, wherein the mixtureof the coarse particles and fine particles is present.
 6. The masonryblock of claim 5, wherein a ratio of the coarse particles to the fineparticles ranges from 2:1 to 1:2.
 7. The masonry block of claim 6,wherein the ratio of the coarse particles to the fine particles is about1:1.
 8. The masonry block of claim 1, which has a unit weight of1000-1250 kg/m³.
 9. The masonry block of claim 1, wherein the masonryblock has a water absorption of 6.0-9.0% as determined by ASTM C 642.10. The masonry block of claim 1, wherein the aggregate is a crushedrecycled concrete material.
 11. The masonry block of claim 1, wherein noaggregate, filler, or additive which comprises a group 13 element ispresent in the masonry block.
 12. The masonry block of claim 11, whereinthe group 13 element is boron.
 13. The masonry block of claim 1, whereinthe crumb rubber is a silanized crumb rubber obtained by treating crumbrubber with at least one selected from the group consisting of(3-aminopropyl)-diethoxy-methylsilane,(3-aminopropyl)-dimethyl-ethoxysilane, and(3-aminopropyl)-trimethoxysilane,(3-glycidoxypropyl)-dimethyl-ethoxysilane, trimethoxysilane and (3mercaptopropyl)-methyl-dimethoxysilane.
 14. The masonry block of claim1, wherein the crumb rubber is a silanized crumb rubber obtained bytreating crumb rubber with an aminosilane selected from the groupconsisting of (3-aminopropyl)-diethoxy-methylsilane,(3-aminopropyl)-dimethyl-ethoxysilane, and(3-aminopropyl)-trimethoxysilane.)
 15. The masonry block of claim 1,wherein the crumb rubber is a silanized crumb rubber obtained bytreating crumb rubber with a glycidoxysilane, which is(3-glycidoxypropyl)-dimethyl-ethoxysilane.
 16. The masonry block ofclaim 1, wherein the crumb rubber is a silanized crumb rubber obtainedby treating crumb rubber with a mercaptosilane selected from the groupconsisting of (3-mercaptopropyl)-trimethoxysilane and(3-mercaptopropyl)-methyl-dimethoxysilane.
 17. The masonry block ofclaim 1, wherein the crumb rubber is carboxylic acid surface modifiedcrumb rubber obtained by treating crumb rubber with hydrogen peroxide.18. The masonry block of claim 1, which has a wt % of crumb rubberranging from 12 to 18%, relative to the total weight of the masonryblock.
 19. The masonry block of claim 1, which consists of the cement,the aggregate, the water and the crumb rubber.